Degeneration of the articular cartilage of the temperomandibular joint (TMJ) leads to pain and debilitation. Tissue-engineered cartilage from a patient's autologous cells has the potential to overcome current therapeutic deficiencies in cartilage repair and joint replacement. However, the mandibular condyle is a complex multilayered structure with a superficial fibrous layer rich in type I collagen and deep cartilage layer rich in type II collagen. Current tissue-engineered cartilage grafts do not possess site-specific structural and mechanical properties compatible with natural condyles. Clinically useful tissue engineered joints could be produced if we had a better understanding of the cellular pathways of mechanical modulation of cartilage matrix composition. It is known that MAP kinase signalling can be mechanically stimulated in chondrocytes and is involved in regulating stages of chondrocyte differentiation and matrix synthesis. The overall objective of the present proposal is to determine the contribution of MAP kinase signaling pathways to mechanical modulation of chondrocyte matrix synthesis in mandibular condyle cells encapsulated in a tissue engineering construct. Our hypothesis is that tailored mechanical stresses will stimulate ex vivo synthesis of mandibular condyle-like matrices via MAP kinase pathways. MAP kinase activity will be examined in polymer constructs encapsulating mandibular derived cells isolated from specific zones of the condyle, using immunohistochemistry and confocal/multiphoton microscopy (Aim 1). The contribution of mechanically induced MAP kinases to synthesis of specific matrix types will be examined using pharmacological MAP kinase inhibitors (Aim 2). The knowledge gained from the proposed studies will contribute to our ability to optimize matrix synthesis in tissue-engineered cartilage. The anticipated data of this R03 application will lead to an R01 application to mechanically enhance the quality of cartilaginous tissue in tissue-engineered mandibular condyles designed for in vivo implantation.